In the 6.0 release, visionfive2_fw_payload.img is now 3.07MiB (3221077 bytes). Unfortunately, on my machine, the size of the uboot mtd partition is not quite big enough to accommodate this:
# cat /proc/mtd
dev: size erasesize name
mtd0: 00040000 00001000 "spl"
mtd1: 00010000 00001000 "uboot-env"
mtd2: 00300000 00001000 "uboot"
mtd3: 00100000 00001000 "data"
#
Note that the "uboot" partition, mtd2 is 0x30_0000 bytes long, or 3MiB; not quite large enough for the FW payload. "data" appears to be unused; I'm guessing the solution here is to combine them in the dts?